Electric engine fan relay install

[DoriDori]

So it's beginning to get seriously hot outside in Ga. I didn't like the idea of my 17 year old fan blades breaking at full speed so I'm in the middle of installing an electric engine fan.

Below is my wire harness I purchased. I want to tap into the blue wire on my aux fan to turn on the electric fan. If I tap the black ground on my harness into the blue going into my aux fan will it work as desired? Or do I need to tap into the blue wire that exits my fan thermo switch.

Thanks for help!




(1997 328ic 5mt)

[gc325is]

Is there a Fan ground wire missing in the dwg? This is not the best fan circuit because it looks like the power ground return line goes thru the fan thermostat switch. The whole idea of using a relay is to NOT control the high current of the fan power lines with the thermostat switch. The temp switch should only see the lower power coil voltage in the relay. Not sure what the Aux blue wire is but it was not designed to handle the extra fan current.


Here is a simple relay circuit Note how fan power goes in the relay and out, and controlled by the coil
The control switch can also be moved between relay pin 86 and ground

[DoriDori]

Thanks for you help! I'm still unsure if I have the same relay is in the DWG above.

Here is the aux fan switch on my radiator (1997 328ic 5mt).

Blk/gry: high speed?
Blk/grn: low speed?
Brown: Ground



Here is the relay im using




According to the DWG below, I think what I'm missing is an ignition source (something only powered when key is in ignition postion). Ive searched some users tapping into a source within the engine harness, IIRC, but is there another wire in a more exposed area under the hood?


- - - Updated - - -

http://forums.bimmerforums.com/forum/showthread.php?618192-Spal-electric-fan-wiring-DIY

According to this thread, one user wired his fan + and - spliced directly into the aux fan power wires. Is this safe?

If not, I will draw ignition from the orange wire in the diagnostic port.

[gc325is]

For a simple circuit just hook pin 85 to the OEM fan power line and pin 86 to ground. Then hook 30 to the battery with a fuse and 87 to your fan power. Connect a ground wire to the new fan return. (I think this is page 11 design but there is no picture) This way you use the OEM fan circuit to power the relay on but use a direct battery line to power the fan. This design is kinda of like page 13 but without doing an ignition splice and temp sensor, you wont need it since the OEM fan circuit already is controlled by them.

http://forums.bimmerforums.com/forum...ing-DIY/page13

Connecting the new fan to the OEM aux fan power is risky since you do not know how much over design BMW did on that circuit. Will it handle an extra 20 amps? But if you just add the relay control line that SB only 50 mA.

This design is also good if you want to add a manual switch to override the temp switch and have the fan on all the time when the car is on

[DoriDori]

For a simple circuit just hook pin 85 to the OEM fan power line and pin 86 to ground. Then hook 30 to the battery with a fuse and 87 to your fan power. Connect a ground wire to the new fan return. (I think this is page 11 design but there is no picture) This way you use the OEM fan circuit to power the relay on but use a direct battery line to power the fan. This design is kinda of like page 13 but without doing an ignition splice and temp sensor, you wont need it since the OEM fan circuit already is controlled by them. http://forums.bimmerforums.com/forum...ing-DIY/page13 Connecting the new fan to the OEM aux fan power is risky since you do not know how much over design BMW did on that circuit. Will it handle an extra 20 amps? But if you just add the relay control line that SB only 50 mA. This design is also good if you want to add a manual switch to override the temp switch and have the fan on all the time when the car is on

Thank you! I will try out page 11 design and report back.

[gc325is]

It looks like this but with pins 85 and 86 swapped but that does not matter.


New wiring:
86 should be 12 v when the OEM fan goes on in this design


Pin 30 = +12V constant (go straight to the positive post in the engine bay, through a 40A fuse)
Pin 85 = GND
Pin 86 = Blue wire on Aux fan
Pin 87 = power to SPAL fan

[DoriDori]

It looks like this but with pins 85 and 86 swapped but that does not matter. New wiring: 86 should be 12 v when the OEM fan goes on in this design Pin 30 = +12V constant (go straight to the positive post in the engine bay, through a 40A fuse) Pin 85 = GND Pin 86 = Blue wire on Aux fan Pin 87 = power to SPAL fan

Thanks for your help! It's all operating thanks to you. Both fans come on on cold start IF AC is on. They are off IF AC is off. After driving 1 hour with highway, traffic, and city, I parked car with engine on/ AC off. Both fans were off. After sitting and idling for couple seconds both fans kicked on. Gives me peace of mind.

My temp gauge rises to this position and barely moves at all. This has always been its Normal temp for me. However, when I pull the cars water temp through the cars obd2 port via a eBay wireless ELM transmitter and iPhone app, the normal temp ranges from 199-214 degrees. Is this a skewed reading on the iPhones app part? Or is that pretty accurate?

[e36fiend]

Thanks for your help! It's all operating thanks to you. Both fans come on on cold start IF AC is on. They are off IF AC is off. After driving 1 hour with highway, traffic, and city, I parked car with engine on/ AC off. Both fans were off. After sitting and idling for couple seconds both fans kicked on. Gives me peace of mind.

My temp gauge rises to this position and barely moves at all. This has always been its Normal temp for me. However, when I pull the cars water temp through the cars obd2 port via a eBay wireless ELM transmitter and iPhone app, the normal temp ranges from 199-214 degrees. Is this a skewed reading on the iPhones app part? Or is that pretty accurate?

That's the temp range my 328 reads with Torque on my android. Needle pegged in the middle.

[gc325is]

FYI for a proper design I away put a diode on the relay otherwise the relay can have problems.
Not sure if people do this anymore. Was your fan a kit or did you assemble the parts your self?

this explains the reason why Quenching Diodes
http://www.bcae1.com/relays.htm

How / where did you mount the extra fan

[Sprouty88]

The flux in the temps is probably accurate. Apparently bmw decided it was a good idea to have the gauge cluster temp needle stay right in the center for the temp range 140-210.

I'm assuming so it wasn't constantly bouncing around and then the average bmw owner would get paranoid and take it back to the shop.


Also, when i wired and installed my Spal electric fan, I tapped into the high temp and low temp signal wires with connectors so in the winter i could put it on high and summer on low.